An example of a machine that manufactures paper products is a box making machine that manufactures a corrugated box from a corrugated sheet cut into a predetermined length in advance. An example of a box making machine includes, in sequence from the upstream side, a feeding unit, a printing unit, a slotter creaser unit, a die cutting unit, a folder gluer unit, and a counter ejector. The printing unit prints a letter and/or a picture on a corrugated sheet fed from the feeding unit, while conveying the corrugated sheet; the slotter creaser unit slots and creases the corrugated sheet to form the corrugated sheet into a box shape; the die cutting unit punches out holes, such as hand holes and air vent holes, in the corrugated sheet and slots and creases the corrugated sheet if desired; the folder gluer unit applies glue on one end of the corrugated sheet and folds the corrugated sheet to glue the both ends; and the counter ejector unit finally piles a predetermined number of corrugated sheets.
If the manufacture of such a paper product includes a step of cutting paper material, paper dust is generated by cutting the paper material. Further, if a paper material (corrugated sheet) cut in advance is processed likewise in the above box making machine, the paper material usually includes paper dust generated by cutting the paper material. Since such paper dust brings harm such as failure in printing, uncleanliness of factories, and failure in sheet conveyance due to stacked paper dust, techniques for removing paper dust has been developed.
For example, Patent Literature 1 discloses a technique to remove paper dust generated when a blank sheet for a multipack packaging box is manufactured by punching the material web into a predetermined shape and concurrently creasing for folding while the web is being conveyed. In this technique, a sheet conveying device transfers the punched sheet into a housing from an inlet to an outlet. During this transfer, air jetting nozzles disposed at both ends of the width direction of the punched sheet being transferred jet high-pressure air to the width direction of the punched sheet and thereby removes paper dust adhering to the sheet. A suction duct connected to the upper portion of the housing suctions air in the housing. With this configuration, little paper dust leaks out of the housing, so that the working environment can be escaped from worsening and the surrounding of the housing can be escaped from becoming dirty.
Patent Literature 2 discloses a configuration in which: a first suction conveyor that transfers products under suction is disposed downstream of a sheet-conveyor that transfers the products fed from a sheet punching device in one direction; a second suction conveyor transferring products under suction is disposed so as to bridge between the sheet-conveyor and the first suction conveyor; and a first suction duct is disposed below the second suction conveyor. With this configuration, a technique is disclosed to remove punched sheet dust remaining on the products by suctioning the products with the first suction duct while the second suction conveyor transfers the products under suction.